Recent progress in the pharmacotherapy of cancer pain.
ABSTRACT Cancer pain can be relatively well managed with primary therapies, according to the WHO ladder. However, different conditions may limit the response to the analgesic drug used, which are mainly oploids. Specifically, adverse effects may prevail against the analgesic activity in the clinical setting. New pharmacological strategies may enable a more satisfactory response to be obtained, in terms of balance between analgesia and adverse effects. The change of route of administration or the use of alternative opioids is a first-line option. The use of adjuvant drugs may also improve analgesia with different mechanisms. Recent studies have demonstrated the value of these alternative approaches. However, most of them require definite confirmation in specific well-designed studies.
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ABSTRACT: The prevalence of pain increases with each decade of life. Pain in the elderly is distinctly different from pain experienced by younger individuals. Cancer is a leading cause of pain; however, other conditions that cause pain such as facet joint arthritis (causing low back pain), polymyalgia rheumatica, Paget's disease, neuropathies, peripheral vascular disease and coronary disease most commonly occur in patients over the age of 50 years. Poorly controlled pain in the elderly leads to cognitive failure, depression and mood disturbance and reduces activities of daily living. Barriers to pain management include a sense of fatalism, denial, the desire to be 'the good patient', geographical barriers and financial limitations. Aging causes physiological changes that alter the pharmacokinetics and pharmacodynamics of analgesics, narrowing their therapeutic index and increasing the risk of toxicity and drug-drug interactions. CNS changes lead to an increased risk of delirium. Assessment among the verbal but cognitively impaired elderly is satisfactorily accomplished with the help of unidimensional and multidimensional pain scales. A comprehensive physical examination and pain history is essential, as well as a review of cognitive function and activities of daily living. The goal of pain management among the elderly is improvement in pain and optimisation of activities of daily living, not complete eradication of pain nor the lowest possible drug dosages. Most successful management strategies combine pharmacological and nonpharmacological (home remedies, massage, topical agents, heat and cold packs and informal cognitive strategies) therapies. A basic principle of the pharmacological approach in the elderly is to start analgesics at low dosages and titrate slowly. The WHO's three-step guideline to pain management should guide prescribing. Opioid choices necessitate an understanding of pharmacology to ensure safe administration in end-organ failure and avoidance of drug interactions. Adjuvant analgesics are used to reduce opioid adverse effects or improve poorly controlled pain. Adjuvant analgesics (NSAIDs, tricyclic antidepressants and antiepileptic drugs) are initiated prior to opioids for nociceptive and neuropathic pain. Preferred adjuvants for nociceptive pain are short-acting paracetamol (acetaminophen), NSAIDs, cyclo-oxygenase-2 inhibitors and corticosteroids (short-term). Preferred drugs for neuropathic pain include desipramine, nortriptyline, gabapentin and valproic acid. Drugs to avoid are pentazocine, pethidine (meperidine), dextropropoxyphene and opioids that are both an agonist and antagonist, ketorolac, indomethacin, piroxicam, mefenamic acid, amitriptyline and doxepin. The type of pain, and renal and hepatic function, alter the preferred adjuvant and opioid choices. Selection of the appropriate analgesics is also influenced by versatility, polypharmacy, severity and type of pain, drug availability, associated symptoms and cost.Drugs & Aging 02/2003; 20(1):23-57. · 2.67 Impact Factor
Article: Advances in the therapy of cancer pain: from novel experimental models to evidence-based treatments[show abstract] [hide abstract]
ABSTRACT: Cancer related pain may be due to the malignant disease itself, or subsequent to treatments, such as surgery, chemotherapy or radiation therapy. The pathophysiology of pain due to cancer may be complex and include a variety of nociceptive, inflammatory, and neuropathic mechanisms. Despite modern advances in pharmacotherapy, cancer pain remains overall under-treated in a world-wide scale, and a main reason is lack of understanding of its pertinent pathophysiology and basic pharmacology. Recently, pertinent animal models have facilitated understanding of the pathobiology and have advanced the pharmacology of cancer pain, with significant translational applicability to clinical practice. Furthermore, quantitative and qualitative systematic reviews, integrating the best available evidence, indicate the validity of treatments that fit into an expanded view of the WHO-analgesic ladder. Appropriate current treatments include a valid therapeutic role of non-opioid and opioid analgesics, adjuvants -such as gabapentin, biphosphonates, palliative radiation therapy and radiopharmaceutical compounds, and interventional pain therapy (including neuraxial drug infusion and verterbroplasty for spine metastases) in selected patients. Overall, experimental animal models simulating cancer pain have been useful in providing pertinent information on the pathophysiology of cancer pain, and provide a testing ground for established and novel therapies, which are validated by clinical evidence. This is clinically significant, considering the epidemiological dimensions and the problematic nature of cancer pain.Signa Vitae. 01/2007;